1. Field of the Invention
The present invention relates to a measuring system for determining scattering parameters of an electrical device under test on a substrate, having a measuring device which has at least one measuring channel and at least one measuring probe which is electrically connected to at least one measuring channel and which is designed for contacting, with or without physical contact, an electrical signal guide belonging to the electrical device under test in the electronic circuit.
2. Description of Related Art
In for example the development of complex planar microwave circuits which are made up of a plurality of sub-circuits, it is useful for the scattering parameters to be determined separately for each sub-circuit or if necessary for individual electronic components. In this way, it is possible for the performance of the various sub-circuits or electronic components to be analyzed and checked individually. The determination of the scattering parameters of an electrical device under test (DUT) which is embedded in a circuit is performed with a modified vector network analyzer (VNA). The accuracy of measurement of the non-contacting vector network analyzer depends chiefly on the repeatability with which the measuring probe can be positioned. By using an automatic on-wafer probe and a motorized probe head, it is possible to set the position of the non-contacting probe, and specifically the distance away of the probe, relative to a planar substrate for measurement.
To enable embedded DUT's to be characterized, the non-contacting probes or the DUT's have to be shifted in position. When this is done, it is necessary for the probes to assume the same positions (in the x, y and z directions) relative to the supply lines to the DUT's or the calibrations standards when measurements are being made on all the DUT's or the calibration standards. Due to unevenness in the planar substrate for measurement, to the coupling probes being obliquely positioned, and so on, it is difficult to ensure that the probes are repeatably positioned. The accuracy of measurement depends on the accuracy of positioning.